Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 187,032	$ 169,736
Other comprehensive (loss) income, net of tax:
Net changes in unrealized (losses) gains on available-for-sale investment securities	(18,812)	3,621
Foreign currency translation adjustments	6,798	1,007
Other comprehensive (loss) income	(12,014)	4,628
COMPREHENSIVE INCOME	$ 175,018	$ 174,364

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature, attributable to parent entity.

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